日期范围键的DynamoDb全局索引查询

我得到与以下代码不匹配的类型:

        var queryRequest = new QueryRequest
        {
            TableName = table,
            IndexName = "CreatedBy-Created-index",
            KeyConditionExpression = "CreatedBy = :createdBy",
            ExpressionAttributeValues = new Dictionary<string, AttributeValue>
            {
                {":createdBy", new AttributeValue {S = filterTasksRequest.CreatedBy.ToLowerInvariant()}}
            }
        };
        if (filterTasksRequest.OnlyShowRecent)
        {
            var earliestDate =
                new DateTimeOffset(DateTime.UtcNow.AddDays(-10)).ToUnixTimeSeconds()
                    .ToString(CultureInfo.InvariantCulture);
            queryRequest.ExpressionAttributeValues[":fromDate"] = new AttributeValue
            {
                N = earliestDate
            };
            queryRequest.KeyConditionExpression +=
                $" AND Created > :fromDate";
        }

一个或多个参数值无效:条件参数类型 亚马逊发电机BV2.AmazonDynamoDBException:一个或多个参数